1. Field of the Invention
The present invention relates to a Stirling cycle refrigerator, particularly to a household Stirling cycle refrigerator which enables rapid production of ice, rapid freezing of food, and successive reiterative production of ice cream.
2. Prior Art
Generally, the refrigerator is one of household appliances, which is capable of producing ice or ice cream, for storing food in frozen in a freezing compartment, and for storing food in a fresh food compartment to maintain freshness. However, in a general household refrigerator, because the temperature in a freezing room is -18.degree. C. the rapid freezing of food is difficult and it usually takes long time of more than 18 hours to produce ice cream, and the successive reiterative production of an ice cream is impossible because the freeze-accelerating material must be used in producing ice cream.
Meanwhile, U.S. Pat. No. 4,522,032 granted to Nakamura discloses a Stirling cycle refrigerator which accomplishes an extremely low temperature in a freezing room. Said Stirling cycle refrigerator comprises a plurality of Stirling cycle refrigerator units, and a countercurrent heat exchanger which enables the heat exchange between the working fluids circulating in said refrigerator units, and by this construction, the freezing temperature can be lowered down to a range of from -269.degree. C. to -270.degree. C. in said Stirling cycle refrigerator.
However, in a general household refrigerator, an extremely low temperature range, from -269.degree. C. to -270.degree. C., is not always necessary because rapid freezing of food and rapid production of ice or ice cream can be effectively achieved by means of a temperature in a range of from -60.degree. C. to -70.degree. C. Particularly in said patented refrigerator, since a separate countercurrent heat exchanger is needed, the construction of the refrigerator is complicated and the manufacturing cost increases.